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Mar-31-06

Mar-31-06Adrian Shields Dr Adrian Butler Dr Paddy Daly Dr Paul HardistyWorleyParsons Komex Imperial College London National Grid Property Worley Parsons Komex

MONITORING OF ORGANIC AND INORGANICPARAMETERS FOR A FULL SCALE IN-SITU PULSED AIRSPARGING PROGRAMME

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Funded by:

Collaborative Research Programme

National Grid Property Holdings Ltd

“Hydro-biological Controls on the Transportand Remediation of Organic Pollutants”

EPSRC - Engineering and Physical Science ResearchCouncil

and by:

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Slide 3MGP 2006

Research Components

Data acquisition, Design, Installation,Testing and operation of Air SpargeTreatment Curtain

KOMEX EUROPE

Development of techniques foridentification of ex-situ and in-situmineralisation rates

Development of variably- saturatedmulti-species contaminant transportmodel

KING’S COLLEGELONDON

IMPERIAL COLLEGELONDON

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Presentation Overview

• SITE CHARACTERISATION hydrogeology

soil/groundwater contaminationremediation works

• PERFORMANCE OF FULL SCALE AIR SPARGING SYSTEM

The Physical System

• CONCLUSIONS

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Slide 5MGP 2006

450

500

550

Scale

, m

500 550 600 650Scale, m

brook

NArea of springs and wet ground

Gasholder Base

Tar Tank

Retort House

Purifiers

Site layout

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Ground Conditions• unconfined fine grained sand aquifer

• underlying clay aquitard at 7 - 10m bgl

• depth to water 1.0 to 1.5m

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Potentiometric contours(0.2m intervals)

OA 1

MW97-1

MW97-2A

MW97-3

MW97-4

MW97-5

MW97-6

MW97-7MW97-8

MW97-9

MW97-10

MW97-11

MW97-12

MW97-13

MW97-14

MW97-15

MW97-16

MW97-17

MW97-18

MW97-19

VMW97-1

VMW97-2

VMW97-3

-575

-475

S ite

Nor

t hin

g s (m

)

Scale, m500 550

475

575

Scale,m

525

Groundwater Flow

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Sources

Total PAHs> 1000 mg/kg

Soil sample

Soil Contamination

550500

475

575

525

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Groundwater Contamination

Benzene > 1000 ug/L

500 550

475

575

525

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500 550Site Eastings (m)

-575

-525

-475

Sit e

Nor

thin

gs (m

)

500 550

475

575

Sources

Total PAHs> 1000 mg/kg

Soil sample

Phase ISource removal

Area of SourceRemoval

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Slide 11MGP 2006

Groundwater Contamination

Benzene > 1000 ug/L

500 550

475

575

525

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7

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Slide 13MGP 2006

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Phase IIAir sparging

-575

-475

500 550

475

575

525

PAH > 0.1 mg/L

Phenol > 1 mg/L

Benzene > 1000 ug/L

Air sparge curtain

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Slide 15MGP 2006

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Slide 16MGP 2006After Johnson (1993)

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After Ji, 1993

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Slide 18MGP 2006

After Ji, 1993

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Slide 19MGP 2006

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AIR IN

Fine Sand

Clay

Unsaturated zone

Saturated zone

Zone of air movement No air movementNo air movement

Groundwater flowGroundwater flowAIR OUT

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Slide 21MGP 2006

AIR IN

Fine Sand

Clay

Unsaturated zone

Saturated zone

Zone of air movement No air movementNo air movement

Groundwater flowGroundwater flowAIR OUT

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Slide 23MGP 2006

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Slide 24MGP 2006

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Factors enhancing the D.O. distribution Diffusion Natural groundwater flow Other Factors: - mounding?

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0

2

4

6

8

10

0 20 40 60 80 100 120

Distance (cm)

Co

nce

ntr

atio

n (

mg

.L-1

)

30

60

90

180

120

360

540

1150

Days

Elapsed

Diffusion: 1D model - Fick’s Law

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Slide 27MGP 2006

Diffusion Limited ability to transfer D.O. beyond air

channels Natural Groundwater Flow

Will have some effect, but not sufficient toexplain broad areas of oxygenated subsurface

Groundwater Mounding – possible.

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Research Goal 1

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Groundwater Elevations, MW98-4

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61

61

62

62

63

63

64

64

1-Jan-00 1-Feb-00 3-Mar-00 3-Apr-00 4-May-00 4-Jun-00 5-Jul-00 5-Aug-00

Time

gro

undw

ate

r ele

vation, m

AO

D30

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Groundwater Elevations, MW98-4, Cycle Detail

61.2

61.4

61.6

61.8

62.0

62.2

62.4

62.6

62.8

63.0

14-Apr-00 15-Apr-00 16-Apr-00 17-Apr-00 18-Apr-00 19-Apr-00 20-Apr-00 21-Apr-00 22-Apr-00 23-Apr-00 24-Apr-00

Time

gro

undw

ate

r ele

vation, m

AO

D

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Groundwater Elevations, MW98-4, Cycle Detail

61.6

61.7

61.8

61.9

62.0

0:00 8:00 16:00 0:00 8:00

Time

gro

undw

ate

r ele

vation m

AO

D

ON

OFF

ON

OFF

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Groundwater Elevation Changes, Sparging and Cessation

61.2

61.4

61.6

61.8

62.0

62.2

62.4

62.6

13:40 14:40 15:40 16:40

Time

gro

un

dw

ate

r e

leva

tio

n,

mA

OD

SW99-04

HA-01

HA-02

injection air pressure 79.3 kPa, flow

rate 1.45 m.s-1

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Research Goal 134

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Groundwater mounding imparts regular to-and-fro movement to groundwater

Provides sufficient movement to explaintransport of D.O. to appreciable distancesbeyond air channels, hence explains broadareas of oxidised soil

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Greater understanding of the physicalprocesses allows refinement in design

Less ‘design contingency’ = cost saving More explicit understanding = greater

acceptance by the Regulator – the system isnot a black box.

Conclusions 36

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Further Work

Harmonisation of physical model, organic and inorganicgeochemical model and microbiological model

Clearer identification of the microbial population, analysis ofspatial variation in population type

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Acknowledgements

• EPSRC - Engineering and Physical ScienceResearch Council

• TES Bretby Laboratories

•National Grid Property Holdings Ltd

• References:Johnson R.L. et al, 1993. An Overview of In Situ Air Sparging. GroundwaterMonitoring and Remediation 1993, pp 127-135Ji, W. et al, 1993. Laboratory Study of Air Sparging: Air Flow Visualisation.Groundwater Monitoring and Remediation 1993, pp 115-126

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Thank you